Cold, compression, elevation and heat have become widely recognized as the standard care for acute musculoskeletal injuries. Of these measures, compression seems to be the most effective deterrent to swelling. (The Physician and Sports Medicine, 1985; 6 (June): 97-106) Applying external compression inhibits seepage of fluid into underlying tissue spaces and disperses excess fluid. Cold reduces swelling, bleeding, and inflammation by constricting blood vessels, slowing cell metabolism, and inhibiting the inflammatory response. Heat, on the other hand, causes vasodilation, which increases blood flow and accelerates the removal of waste products.
The use of compression and hot/cold therapy for the treatment of injury and illness such as the reduction of post surgery edema, musculoskeletal injuries, including trauma, sprains, strains, ligament and tendon damage, and their use in the treatment of arthritis, pain control, respiratory and circulatory problems have been well documented.
There are numerous devices which are designed to cool or heat a bodily injury, by holding a therapeutic thermopack adjacent an injured limb, as described in U.S. Pat. Nos. 5,020,711 to Kelly, 4,592,358 to Westplate and 4,886,063 to Crews.
These devices all have the disadvantage that they do not deliver an adequate therapeutic effect to the appropriate anatomical areas. Some are bulky and non-portable, while others tend to slip out of position due to their shape and design, requiring the patient to be relatively immobile while wearing them. Failure of the compress to conform slowly and to retain close contact once positioned, results in irregular heating and cooling of the skin area. The problem often results in irregular or non-uniform healing of the skin, increased swelling, and the like.
To overcome this problem, devices are available which incorporate a plurality of small cells interconnected by passageways. For example, U.S. Pat. Nos. 4,753,241 to Brannigan and 4,846,176 to Golden disclose a temperature maintaining device consisting of an upper surface of a flexible material that is sealed to a lower surface of flexible material to form a plurality of chambers and interconnected passageways. The chambers and passageways are filled with a thermal responsive medium used to heat or cool the body.
Despite their tendency to cool or heat the body, even these newer wraps had drawbacks which have prevented them for attaining widespread acceptance. For instance, most of the previous wraps include rather complex interior structures for maintaining the cold pack in a central position. These complex structures require time-consuming manufacturing procedures and increase the overall cost of the product. In addition, the wraps are generally not washable, and thus become dirty and perspiration-soaked after several wearings.
Recent medical studies suggest that ice has a more limited role in the reduction of swelling as compared to external compression. (Journal of Bone Joint Surgery, 1974; 56 (December) 1586-1591) Therefore, physicians, physical therapists, and athletic trainers have placed more importance on compression therapy.
Various compression devices utilize air compression with one or more inflatable bladders that form a compressive-force upon the injured area. These include U.S. Pat. Nos. 4,280,489, 4,628,945 and 5,125,400.
Other compression devices utilize both an air inflatable bladder and a thermally responsive medium, where the air bladder is positioned outside the thermal medium to provide a uniform compressive force upon the thermal medium and the injured body part.
U.S. Pat. No. 4,993,409 to Grim discloses a back support consisting of a thermally responsive gel bladder with three air inflatable chambers positioned outside the gel bladder to provide a compressive force upon the lower back.
U.S. Pat. No. 5,088,478 to Grim discloses an ankle brace worn under a shoe, that has a gel bladder with a second bladder inflatable with air positioned outside the first bladder to provide a uniform compressive force upon the bladder filled with gel.
U.S. Pat. Nos. 3,901,225 to Scone, 3,561,435 to Nicholson, and 3,548,819 to Davis disclose air inflatable splints with an air bladder positioned outside a removable thermo pack, where the air bladder provides a compressive force upon the thermo pack which braces and conforms the device.
The inability to measure or control compression levels--a disadvantage of all existing air-inflatable splints and braces--can lead to over pressure and injury or under pressure and inadequate treatment. Over pressurization can cause skin ischemia, loss of blood circulation, and increased trauma. In addition, excessive compression over a cold medium has been known to cause nerve damage. (The Journal of Athletic Training, 1992; 27: 235-237)
To alleviate these problems, air compression braces and splints were designed with pressure monitors. These include U.S. Pat. Nos. 2,699,165 to Ferrier, 2,113,253 to Grey, and 4,039,039 to Gottfried.
The problem with these air compression braces is that they all utilize external pressure monitoring devices that are bulky, non-portable, and involve complex manufacturing processes. These devices are primarily used by patients who are bedridden or immobile.
Another embodiment of a compression brace is disclosed in U.S. Pat. No. 5,025,781 which has a bleed hole that continuously releases pressure. The problem with this device is that it cannot keep a constant pressure and relies on an external electric pump to re-pressurize.
Another embodiment of a compression brace having an external pump source is the sequential pneumatic pressure sleeve. Sequential compression is used because of its ability to provide a graduated application of pressure, i.e., greater pressure to the lower leg and reduced pressure to the upper leg. Devices with the foregoing description are disclosed in U.S. Pat. Nos. 4,013,069 and 4,030,488 to Hasty, and 5,117,812 to McWhorter.
These braces all have the disadvantages that they require an external, electric pump to provide the compression. The pump is bulky, relatively non-portable, involves complex manufacturing and is expensive.
Another disadvantage of the above-mentioned patents is that they do not provide for the unrestricted movement of the joint through its full range of motion. The air bladders stiffen the brace and restrict or hinder the free movement of the joint.